Some restaurant meals contain whopping amounts of salt, which is used as a preservative and to enhance flavor and texture. Chili’s fajita chicken quesadilla with rice and black beans, sour cream and pico de gallo has 5,300 milligrams of salt.

The analysis did find that nutritional labels are an accurate reflection of sodium levels. In some cases, salt is added to low-fat foods to compensate for lack of flavor, and checking the label is the only way to know.

Many foods perceived to be salty contain less sodium than some low-fat foods, the analysis found. For example, a quarter-cup of Planters mixed salted nuts contains 110 milligrams of sodium, less than half the sodium in seven Kraft Snackables cheddar and Monterey Jack reduced-fat cheese cubes, which have 270 milligrams of sodium.

Salt increases the risk of developing high blood pressure and related cardiovascular problems, and federal dietary guidelines recommend limiting salt intake to 2,300 milligrams a day. The average American consumes 2,900 to 4,300 milligrams of sodium a day.

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Sodium in food comes from ingredients other than table salt, including monosodium glutamate, baking soda, sodium nitrate and other additives; only about 10 percent of the sodium people consume occurs naturally.

The American Medical Association has estimated that 150,000 lives could be saved each year if Americans cut their salt intake in half, and the Center for Science in the Public Interest, a consumer watchdog group, has petitioned the Food and Drug Administration to regulate salt in foods.

According to the center, while some companies have reduced sodium in their products in recent years, amounts have spiked in other products over the same time period. A serving of french fries at Hardee’s, the fast food chain, contains three times as much sodium as it did in 2005, according to C.S.P.I.

The sodium reductions in some places and increases in others "basically cancel each other out,” said C.S.P.I. executive director Michael F. Jacobson. Sodium levels may vary in a given product from brand to brand, but “overall sodium levels haven’t changed,” he added.

The consumer-watchdog organization also conducted a taste test of lower-salt versions of foods that are usually high in sodium. The most popular ones were Dietz & Watson Gourmet Lite turkey breast (with the skin on), with 240 milligrams of sodium per two-ounce serving, and the Silver Palate Salad Splash Balsamic Country salad dressing, which has 15 milligrams of sodium in two tablespoons.